Catalyst and process for oxychlorination of ethylene to dichloroethane

ABSTRACT

In an oxychlorination process of the type where ethylene is converted to 1,2-dichloroethane in the presence of a supported copper catalyst, the improvement comprising: the use of a supported catalyst prepared by (i) impregnating, within a first step, an alumina support with a first aqueous solution including copper, an alkaline earth metal, and an alkali metal to thereby form a first catalyst component; and (ii) impregnating, within a subsequent step, the first catalyst component with a second aqueous solution including copper and alkaline earth metal, where the second aqueous solution is substantially devoid of alkali metal, to thereby form the supported catalyst.

This application claims the benefit of U.S. Provisional Application Ser.No. 61/798,872, filed on Mar. 15, 2013, which is incorporated herein byreference.

FIELD OF THE INVENTION

Embodiments of the invention relate to catalysts for oxychlorination ofethylene to dichloroethane. The catalysts advantageously exhibit lessstickiness, especially at high copper loadings, and they are thereforeadvantageously useful in baffled-bed reactors.

BACKGROUND OF THE INVENTION

Oxychlorination is the process where ethylene is converted to1,2-dichloroethane. This reaction can take place in a vapor phasereaction over a fluidized catalyst bed in a mixture of ethylene,hydrogen chloride, and oxygen (e.g. pure oxygen or air). Coppercatalysts supported on alumina supports are well known in the art ofoxychlorination catalysts. For example, U.S. Pat. No. 5,292,703 teachesa catalyst for oxychlorination of ethylene to produce1,2-dichloroethane, where the catalyst includes copper chloride, atleast one alkali metal, at least one rare earth metal, and at least oneGroup HA (i.e. alkaline earth metal) metal on a support such alumina.This catalyst purportedly results in high percent ethylene efficiency,high dichloroethane product purity, and high percent HCl conversionwithout exhibiting catalyst stickiness. As the skilled personunderstands, catalyst stickiness refers to an agglomeration of catalystparticles and can deleteriously impact ethylene and hydrogen chloridefeedstock efficiencies in a fluid bed oxychlorination process.

U.S. Publ. No. 2009/0054708 discloses an oxychlorination catalyst thatis designed for use in a baffled bed reactor. The catalyst includes 5.5to 14 wt % copper, alkaline earth metal, alkali metal, and rare earthmetal, with the limitation that the amount of alkali metal is no higherthan 1 wt %. The reference discloses that it has been found thatsignificant levels of alkali metal in the catalyst increasessusceptibility to stickiness.

SUMMARY OF THE INVENTION

Embodiments of the invention provide an oxychlorination process of thetype where ethylene is converted to 1,2-dichloroethane in the presenceof a supported copper catalyst, the improvement comprising: the use of asupported catalyst prepared by (i) impregnating, within a first step, analumina support with a first aqueous solution including copper,optionally an alkaline earth metal, and an alkali metal to thereby forma first catalyst component; and (ii) impregnating, within a subsequentstep, the first catalyst component with a second aqueous solutionincluding copper and alkaline earth metal, where the second aqueoussolution is substantially devoid of alkali metal, to thereby form thesupported catalyst.

Other embodiments of the invention provide a process for producing acatalyst for the oxychlorination of ethylene to 1,2-dichloroethane, theprocess comprising the steps of impregnating, within a first step, analumina support with a first aqueous solution including copper, analkaline earth metal, and an alkali metal to thereby form a firstcatalyst component and impregnating, within a subsequent step, the firstcatalyst component with a second aqueous solution including copper andalkaline earth metal, where the second aqueous solution is substantiallydevoid of alkali metal, to thereby form the supported catalyst.

Other embodiments of the invention provide an oxychlorination processcomprising the step of converting ethylene to 1,2-dichloroethane in thepresence of a catalyst, oxygen, and hydrogen chloride, where thecatalyst is produced by impregnating, within a first step, an aluminasupport with a first aqueous solution including copper, an alkalineearth metal, and an alkali metal to thereby form a first catalystcomponent; and impregnating, within a subsequent step, the firstcatalyst component with a second aqueous solution including copper andalkaline earth metal, where the second aqueous solution is substantiallydevoid of alkali metal, to thereby form the supported catalyst.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Embodiments of the invention are based, at least in part, on thediscovery of a supported catalyst for oxychlorination of ethylene todichloroethane including copper, alkali metal, alkaline earth metal, andoptionally rare earth metal. It has unexpectedly been discovered thatthe techniques employed to fabricate the supported catalyst, especiallythe techniques employed to impregnate the support with the variousmetals, impacts catalyst stickiness, especially at relatively highcopper loadings. Thus, the fabrication techniques can be manipulated,especially with regard to the alkali metal and alkaline earth metal, toproduce technologically useful supported catalysts that do notdeleteriously suffer from stickiness. Moreover, while the prior artsuggests that alkali metals at greater than 1 wt % have a deleteriousimpact on stickiness and negligible impact and catalyst efficiency, ithas been found that the presence of alkali metal at levels greater than1 wt % can be advantageous without deleteriously impacting stickiness,and therefore certain embodiments include supported catalyst withgreater than 1 wt % alkali metal. In one or more embodiments, thesupported catalyst is advantageously useful in baffled bed reactors.Also, in one or more embodiments, the catalyst compositionsadvantageously can be used in an oxychlorination process to yield higherHCl conversion, lower chlorinated by-byproducts, and/or lower oxidationby-products. Still further, the catalyst composition may advantageouslybe used in an oxychlorination process that can operate at relativelyhigh temperatures without producing deleterious levels of carbon oxides.

Catalyst Composition

In one or more embodiments, the catalyst composition, which may also bereferred to as a supported catalyst, includes an active catalyst metal,catalyst promoters, and a catalyst support. As will be described ingreater detail below, the catalyst composition may be prepared byimpregnating the support with aqueous solutions carrying one or more ofthe active catalyst metal and catalyst promoters by a method commonlyknown as incipient wetness impregnation.

In one or more embodiments, the active catalyst metal includes copper inthe form of copper salts. In one or more embodiments, useful coppersalts include, but are not limited to, copper (II) halides such ascopper (II) chlorides. Practice of one or more embodiments of thepresent invention is not, however, limited by the selection of anyparticular copper salt, and therefore reference can be made to U.S. Pat.No. 5,292,703 and U.S. Publ. No. 2009/0054708, which are incorporatedherein by reference.

As will be explained in greater detail below, the catalyst compositionis described based upon weight percentages. The composition can also bedescribed based upon moles per kilogram catalyst, which the skilledperson can easily calculate. Nonetheless, for ease of description, theweight percentages described herein are provided in moles per kilogramcatalyst within Tables I-III herein. Those skilled in the art willappreciate that the moles per kilogram catalyst provided in the tablesbelow are applicable to any disclosure of weight for the purpose of thisspecification.

In one or more embodiments, the catalyst composition includes greaterthan 5.0, in other embodiments greater than 6.0, in other embodimentsgreater than 7.0, and in other embodiments greater than 8.0 wt % coppermetal based upon the entire weight of the catalyst composition, which asdescribed above includes the catalyst support, metals, and ligands orcounter anions associated with any given metal additive. In these orother embodiments, the catalyst composition includes less than 12, inother embodiments less than 11, in other embodiments less than 10, andin other embodiments less than 9 wt % copper metal based upon the entireweight of the catalyst composition. In one or more embodiments, thecatalyst composition includes from about 5.0 to about 12, in otherembodiments from about 6.0 to about 11, in other embodiments from about7.0 to about 10.5, and in other embodiments from about 8.0 to about 10.0wt % copper metal based upon the entire weight of the catalystcomposition.

In one or more embodiments, a catalyst promoter or complementary metalincludes alkali metal in the form of alkali metal salts. In one or moreembodiments, useful alkali metal salts include, but are not limited to,halides of lithium, sodium, and potassium. In particular embodiments,potassium chloride is employed. Practice of one or more embodiments ofthe present invention is not, however, limited by the selection of anyparticular alkali metal salt, and therefore reference can be made toU.S. Pat. No. 5,292,703 and U.S. Publ. No. 2009/0054708, which areincorporated herein by reference.

In one or more embodiments, the catalyst composition includes greaterthan 0.25, in other embodiments greater than 0.5, in other embodimentsgreater than 1.0, and in other embodiments greater than 1.05 wt % alkalimetal based upon the entire weight of the catalyst composition, which asdescribed above includes the catalyst support, metals, and ligands orcounter anions associated with any given metal additive. In these orother embodiments, the catalyst composition includes less than 1.6, inother embodiments less than 1.5, in other embodiments less than 1.4, andin other embodiments less than 1.3 wt % alkali metal based upon theentire weight of the catalyst composition. In one or more embodiments,the catalyst composition includes from about 0.25 to about 1.6, in otherembodiments from about 0.5 to about 1.5, in other embodiments from about1.0 to about 1.4, and in other embodiments from about 1.05 to about 1.3wt % alkali metal based upon the entire weight of the catalystcomposition. The foregoing wt %(s) are based upon the use of potassiumas the alkali metal; where another alkali metal is substituted for thepotassium, the foregoing wt %(s) will be adjusted for the difference inelemental weight of the different alkali metal, keeping a molarequivalent to the moles of potassium present in any given wt %.

In one or more embodiments, a catalyst promoter or complementary metalincludes alkaline earth metal in the form of alkaline earth metal salts.In one or more embodiments, useful alkaline earth metal salts include,but are not limited to, halides of beryllium, magnesium, and calcium. Inparticular embodiments, magnesium dichloride is employed. Practice ofone or more embodiments of the present invention is not, however,limited by the selection of any particular alkaline earth metal salt,and therefore reference can be made to U.S. Pat. No. 5,292,703 and U.S.Publ. No. 2009/0054708, which are incorporated herein by reference.

In one or more embodiments, the catalyst composition includes greaterthan 0.25, in other embodiments greater than 0.5, in other embodimentsgreater than 0.75, and in other embodiments greater than 1.0 wt %alkaline earth metal based upon the entire weight of the catalystcomposition, which as described above includes the catalyst support,metals, and ligands or counter anions associated with any given metaladditive. In these or other embodiments, the catalyst compositionincludes less than 3.0, in other embodiments less than 2.5, in otherembodiments less than 2.25, and in other embodiments less than 2.0 wt %alkaline earth metal based upon the entire weight of the catalystcomposition. In one or more embodiments, the catalyst compositionincludes from about 0.25 to about 3.0, in other embodiments from about0.5 to about 2.5, in other embodiments from about 0.75 to about 2.25,and in other embodiments from about 1.0 to about 2.0 wt % alkaline earthmetal based upon the entire weight of the catalyst composition. Theforegoing wt %(s) are based upon the use of magnesium as the alkalineearth metal; where another alkaline earth metal is substituted for themagnesium, the foregoing wt %(s) will be adjusted for the difference inelemental weight of the different alkaline earth metal, keeping a molarequivalent to the moles of magnesium present in any given wt %.

In one or more embodiments, a catalyst promoter or complementary metalincludes rare earth metal in the form of rare earth metal salts. In oneor more embodiments, useful rare earth metal salts include, but are notlimited to, halides of lanthanum, cerium, and neodymium. In particularembodiments, lanthanum(III) and cerium(III) chlorides are employed.Practice of one or more embodiments of the present invention is not,however, limited by the selection of any particular rare earth metalsalt, and therefore reference can be made to U.S. Pat. No. 5,292,703 andU.S. Publ. No. 2009/0054708, which are incorporated herein by reference.

In one or more embodiments, the catalyst composition includes greaterthan 0, in other embodiments greater than 0.5, in other embodimentsgreater than 0.75, and in other embodiments greater than 1.0 wt % rareearth metal based upon the entire weight of the catalyst composition,which as described above includes the catalyst support, metals, andligands or counter anions associated with any given metal additive. Inthese or other embodiments, the catalyst composition includes less than3.0, in other embodiments less than 2.5, in other embodiments less than2.3, in other embodiments less than 2.2, and in other embodiments lessthan 2.0 wt % rare earth metal based upon the entire weight of thecatalyst composition. In one or more embodiments, the catalystcomposition includes from about 0 to about 2.5, in other embodimentsfrom about 0.75 to about 2.3, and in other embodiments from about 1.0 toabout 2.2 wt % rare earth metal based upon the entire weight of thecatalyst composition. The foregoing wt %(s) are based upon the use oflanthanum and cerium as the rare earth metal; where another rare earthmetal is substituted for the lanthanum and/or cerium, the foregoing wt%(s) will be adjusted for the difference in elemental weight of thedifferent rare earth metal, keeping a molar equivalent to the moles oflanthanum and/or cerium present in any given wt %.

Support Materials

Practice of one or more embodiments of the present invention are limitedby the selection of any particular catalyst support. In this regard,U.S. Pat. No. 5,292,703 and U.S. Publ. Nos. 2009/0054708, 2009/0298682,2010/0274061, 2006/0129008, and 2004/0192978 are incorporated herein byreference.

In particular embodiments, alumina supports are employed. Aluminasupports useful in oxychlorination catalysts are well known in the artand commercially available under the tradenames Catalox and Puralox(Sasol).

Preparation of Catalyst Materials

As suggested above, the supported catalyst materials of the presentinvention may be prepared by impregnating the support with aqueoussolutions carrying one or more of the active catalyst metal and catalystpromoters by incipient wetness impregnation. For purposes of thisspecification, and unless otherwise stated, the technique ofimpregnating the support should be understood in its broadest sense andincludes wetting the support over a wide range (e.g. 80% to 115% of itspore volume). In one or more embodiments, the support treated with theaqueous solution, which becomes wetted, can be subsequently dried. Inone or more embodiments, the supported catalyst or any precursor can becalcined.

In one or more embodiments, the step of impregnating the support takesplace in multiple steps. In other words, the support is impregnated intwo or more impregnation steps to produce the desired supportedmaterial. In one or more embodiments, a two-step impregnation process isemployed using first and second aqueous solutions containing coppersalts and specific promoter metals. As used herein, reference to thefirst impregnation step will correspond to the use of the first aqueoussolution, and reference to a second impregnation step will correspond tothe use of the second aqueous solution.

In one or more embodiments, the two impregnation steps are performedusing standard techniques for multiple impregnations of a catalystsupport. In one or more embodiments, after the first impregnation step,the catalyst may be dried prior to the second impregnation step. In oneor more embodiments, the catalyst material is dried to a point where itincludes less than 5.0%, in other embodiments less than 3.0%, and inother embodiments less than 1.0% water on a weight basis before thesecond impregnation step. In one or more embodiments, the catalystmaterial is dried after the first impregnation step to a level wheresufficient pore volume is achieved so as to allow the secondimpregnation step to deposit the desired amount of material. Followingthe second impregnation step, the catalyst material is again dried. Inone or more embodiments, after the second impregnation step, thecatalyst material is dried to a point where it includes less than 5.0%,in other embodiments less than 3.0%, and in other embodiments less than1.0% water on a weight basis.

First Solution

In one or more embodiments, the first solution includes a copper salt,an alkali metal salt, optionally an alkaline earth metal salt, andoptionally a rare earth metal salt. In particular embodiments, the firstsolution includes a copper salt, an alkali metal salt, and an alkalineearth metal salt. And, in particular embodiments, the first solutionincludes a copper salt, an alkali metal salt, an alkaline earth metalsalt, and a rare earth metal salt.

In one or more embodiments, the concentration of the copper salt withinthe first solution is calculated to provide the support, after drying,with a copper metal concentration of greater than 2.5, in otherembodiments greater than 3.3, in other embodiments greater than 3.7, andin other embodiments greater than 4.0 wt % copper metal based upon theentire weight of the catalyst composition, which as described aboveincludes the catalyst support, metals, and ligands or counter anionsassociated with any given metal additive. In these or other embodiments,the concentration of the copper salt within the first solution iscalculated to provide the support, after drying, with a copper metalconcentration of less than 6.5, in other embodiments less than 5.5, andin other embodiments less than 5.0 wt % copper metal based upon theentire weight of the catalyst composition. In one or more embodiments,the concentration of the copper salt within the first solution iscalculated to provide the support, after drying, with a copper metalconcentration of about 2.5 to about 6, in other embodiments from about3.3 to about 5.5, and in other embodiments from about 4.0 to about 5.0wt % copper metal based upon the entire weight of the catalystcomposition. Stated another way, the foregoing represent the wt %(s)copper on the dried support following the first impregnation step.

In one or more embodiments, the concentration of the alkali metal saltwithin the first solution is calculated to provide the support, afterdrying, with a alkali metal concentration of greater than 0.25, in otherembodiments greater than 0.5, in other embodiments greater than 1.0, andin other embodiments greater than 1.05 wt % alkali metal based upon theentire weight of the catalyst composition, which as described aboveincludes the catalyst support, metals, and ligands or counter anionsassociated with any given metal additive. In these or other embodiments,the concentration of the alkali metal salt within the first solution iscalculated to provide the support, after drying, with an alkali metalconcentration of less than 1.6, in other embodiments less than 1.5, inother embodiments less than 1.4, and in other embodiments less than 1.3wt % alkali metal based upon the entire weight of the catalystcomposition. In one or more embodiments, the concentration of the alkalimetal salt within the first solution is calculated to provide thesupport, after drying, with an alkali metal concentration of from about0.25 to about 1.6, in other embodiments from about 0.5 to about 1.5, inother embodiments from about 1.0 to about 1.4, in other embodiments fromabout 1.05 to about 1.3 wt % alkali metal based upon the entire weightof the catalyst composition. The foregoing wt %(s) are based upon theuse of potassium as the alkali metal; where another alkali metal issubstituted for the potassium, the foregoing wt %(s) will be adjustedfor the difference in elemental weight of the different alkali metal,keeping a molar equivalent to the moles of potassium present in anygiven wt %. Stated another way, the foregoing represent the wt %(s)alkali metal on the dried support following the first impregnation step.

In one or more embodiments, the concentration of the alkaline earth saltwithin the first solution is calculated to provide the support, afterdrying, with a alkaline earth metal concentration of greater than 0.5,in other embodiments greater than 0.7, and in other embodiments greaterthan 0.85, and in other embodiments greater than 1.0 wt % alkaline earthmetal based upon the entire weight of the catalyst composition, which asdescribed above includes the catalyst support, metals, and ligands orcounter anions associated with any given metal additive. In these orother embodiments, the concentration of the alkaline earth salt withinthe first solution is calculated to provide the support, after drying,with a alkaline earth metal concentration of less than 2.5, in otherembodiments less than 2.0, and in other embodiments less than 1.7, andin other embodiments less than 1.5 wt % alkaline earth metal based uponthe entire weight of the catalyst composition. In one or moreembodiments, the concentration of the alkaline earth salt within thefirst solution is calculated to provide the support, after drying, witha alkaline earth metal concentration of 0%. In one or more embodiments,the concentration of the alkaline earth salt within the first solutionis calculated to provide the support, after drying, with a alkalineearth metal concentration from about 0.5 to about 2.5, in otherembodiments from about 0.7 to about 2.0, and in other embodiments fromabout 0.85 to about 1.7, and in other embodiments from about 1.0 toabout 1.5 wt % alkaline earth metal based upon the entire weight of thecatalyst composition. The foregoing wt %(s) are based upon the use ofmagnesium as the alkaline earth metal; where another alkaline earthmetal is substituted for the magnesium, the foregoing wt %(s) will beadjusted for the difference in elemental weight of the differentalkaline earth metal, keeping a molar equivalent to the moles ofmagnesium present in any given wt %. Stated another way, the foregoingrepresent the wt %(s) alkaline earth on the dried support following thefirst impregnation step.

In one or more embodiments, the concentration of the rare earth saltwithin the first solution is calculated to provide the support, afterdrying, with a rare earth metal concentration of greater than 0, inother embodiments greater than 0.5, and in other embodiments greaterthan 0.75, and in other embodiments greater than 1.0 wt % rare earthmetal based upon the entire weight of the catalyst composition, which asdescribed above includes the catalyst support, metals, and ligands orcounter anions associated with any given metal additive. In these orother embodiments, the concentration of the rare earth salt within thefirst solution is calculated to provide the support, after drying, witha rare earth metal concentration of less than 2.5, in other embodimentsless than 2.3, in other embodiments less than 2.2, and in otherembodiments less than 2.0 wt % rare earth metal based upon the entireweight of the catalyst composition. In one or more embodiments, theconcentration of the rare earth salt within the first solution iscalculated to provide the support, after drying, with a rare earth metalconcentration from about 0 to about 2.5, in other embodiments from about0.5 to about 2.25, in other embodiments from about 0.75 to about 2.0,and in other embodiments from about 1.0 to about 2.0 wt % rare earthmetal based upon the entire weight of the catalyst composition. Statedanother way, the foregoing represent the wt %(s) rare earth metal on thedried support following the first impregnation step. The foregoing wt%(s) are based upon the use of lanthanum and cerium as the rare earthmetal; where another rare earth metal is substituted for the lanthanumand/or cerium, the foregoing wt %(s) will be adjusted for the differencein elemental weight of the different rare earth metal, keeping a molarequivalent to the moles of lanthanum and/or cerium present in any givenwt %.

Second Solution

In one or more embodiments, the second solution includes a copper salt,an alkaline earth metal salt, optionally a rare earth metal salt, and issubstantially devoid of alkali metal. In particular embodiments, thesecond solution includes a copper salt, an alkaline earth metal salt, arare earth metal salt, and is substantially devoid of alkali metal. Inyet other particular embodiments, the second solution includes a coppersalt, an alkaline earth metal salt, and is substantially devoid of analkali metal and a rare earth metal.

In one or more embodiments, the concentration of the copper salt withinthe second solution is calculated to provide the product of the firstimpregnation, after drying, with an additional copper metalconcentration of greater than 1.5, in other embodiments greater than2.5, in other embodiments greater than 3.3, in other embodiments greaterthan 3.7, and in other embodiments greater than 4.0 wt % copper metalbased upon the entire weight of the catalyst composition, which asdescribed above includes the catalyst support, metals, and ligands orcounter anions associated with any given metal additive. In these orother embodiments, the concentration of the copper salt within thesecond solution is calculated to provide the product of the firstimpregnation, after drying, with an additional copper metalconcentration of less than 6.5, in other embodiments less than 5.5, andin other embodiments less than 5.0 wt % copper metal based upon theentire weight of the catalyst composition. In one or more embodiments,the concentration of the copper salt within the second solution iscalculated to provide the product of the first impregnation, afterdrying, with an additional copper metal concentration of about 2.5 toabout 6.5, in other embodiments from about 3.3 to about 5.5, and inother embodiments from about 4.0 to about 5.0 wt % copper metal basedupon the entire weight of the catalyst composition.

The skilled person will appreciate that the additional metal (e.g.additional copper) imparted by the second impregnation step (i.e. fromthe second solution) can be calculated based upon the differentialbetween the weight percentage of the metal based upon the entire weightof the catalyst composition after the first impregnation step and theweight percentage of the metal based upon the entire weight of thecatalyst composition after the second impregnation step. For example, ifit is assumed that the weight percentage of copper after the firstimpregnation step is 4.5 wt %, based upon the total weight of thecatalyst composition after the first impregnation step, and that theweight percentage of copper after the second impregnation step is 8.5 wt%, based upon the total weight of the catalyst composition after thesecond impregnation step, then the total additional weight percentcopper provided by the second impregnation step is 4.0 wt %, based uponthe total weight of the catalyst composition after the secondimpregnation step.

In one or more embodiments, the concentration of the alkaline earth saltwithin the second solution is calculated to provide the product of thefirst impregnation, after drying, with an additional alkaline earthmetal concentration of greater than 0.06, in other embodiments greaterthan 0.125, and in other embodiments greater than 0.18, in otherembodiments greater than 0.20, in other embodiments greater than 0.22,and in other embodiments greater than 0.25 wt % alkaline earth metalbased upon the entire weight of the catalyst composition, which asdescribed above includes the catalyst support, metals, and ligands orcounter anions associated with any given metal additive. In these orother embodiments, the concentration of the alkaline earth salt withinthe second solution is calculated to provide the product of the firstimpregnation, after drying, with an additional alkaline earth metalconcentration of less than 1.5, in other embodiments less than 1.3, andin other embodiments less than 1.0 wt % alkaline earth metal based uponthe entire weight of the catalyst composition. In one or moreembodiments, the concentration of the alkaline earth salt within thesecond solution is calculated to provide the product of the firstimpregnation, after drying, with an additional alkaline earth metalconcentration from about 0.06 to about 1.5, in other embodiments fromabout 0.18 to about 1.3, and in other embodiments from about 0.25 toabout 1.0 wt % alkaline earth metal based upon the entire weight of thecatalyst composition. The foregoing wt %(s) are based upon the use ofmagnesium as the alkaline earth metal; where another alkaline earthmetal is substituted for the magnesium, the foregoing wt %(s) will beadjusted for the difference in elemental weight of the differentalkaline earth metal, keeping a molar equivalent to the moles ofmagnesium present in any given wt %.

In one or more embodiments, the amount of alkaline earth metal impartedby the second impregnation step (i.e. from the second solution) isquantified, either alone or in combination with the parameters set forthabove, based upon the amount of copper imparted by the secondimpregnation step. Stated another way, the invention can be definedbased upon the molar ratio of alkaline earth metal (e.g. magnesium) tocopper added in the second impregnation step. In one or moreembodiments, the molar ratio of alkaline earth (e.g. magnesium) tocopper added in the second impregnation step is greater than 0.19, inother embodiments greater than 0.22, in other embodiments greater than0.24, in other embodiments greater than 0.26, and in other embodimentsgreater than 0.28. In one or more embodiments, the molar ratio ofalkaline earth to copper added in the second impregnation step is fromabout 0.20 to about 0.50, in other embodiments is from about 0.22 toabout 0.45, in other embodiments is from about 0.24 to about 0.40, andin other embodiments is from about 0.26 to about 0.36.

In one or more embodiments, the concentration of the rare earth saltwithin the second solution is calculated to provide the product of thefirst impregnation, after drying, with a rare earth metal concentrationof greater than 0, in other embodiments greater than 0.5, and in otherembodiments greater than 0.75, and in other embodiments greater than 1.0wt % rare earth metal based upon the entire weight of the catalystcomposition, which as described above includes the catalyst support,metals, and ligands or counter anions associated with any given metaladditive. In these or other embodiments, the concentration of the rareearth salt within the second solution is calculated to provide theproduct of the first impregnation, after drying, with a rare earth metalconcentration of less than 2.5, in other embodiments less than 2.3, inother embodiments less than 2.2, and in other embodiments less than 2.0wt % rare earth metal based upon the entire weight of the catalystcomposition. In one or more embodiments, the concentration of the rareearth salt within the second solution is calculated to provide theproduct of the first impregnation, after drying, with a rare earth metalconcentration from about 0 to about 2.5, in other embodiments from about0.5 to about 2.25, in other embodiments from about 0.75 to about 2.0,and in other embodiments from about 1.0 to about 2.0 wt % rare earthmetal based upon the entire weight of the catalyst composition. Theforegoing wt %(s) are based upon the use of lanthanum and cerium as therare earth metal; where another rare earth metal is substituted for thelanthanum and/or cerium, the foregoing wt %(s) will be adjusted for thedifference in elemental weight of the different rare earth metal,keeping a molar equivalent to the moles of lanthanum and/or ceriumpresent in any given wt %.

As described above, the second solution is substantially devoid ofalkali metal. This includes, by definition, being substantially devoidof alkali metal and any salts or other compounds including alkali metal.Substantially devoid, as it is used with respect to the alkali metalincludes that amount or less of alkali metal that would not have anappreciable impact on the supported catalyst, especially with regard topractice of this invention. This includes a requirement that the amountof alkali metal in the second solution is lower than that amount thatwill have a deleterious impact on the stickiness of the supportedcatalyst produced according to this invention. In one or moreembodiments, the second solution is devoid of alkali metal. In one ormore embodiments, the concentration of any alkali metal, or alkali metalsalt, within the second solution is less than that amount that wouldprovide the support, after drying, with an additional alkali metalconcentration of 0.5, in other embodiments 0.3, in other embodiments0.1, or in other embodiments 0.05 wt % alkali metal.

As described above, in certain embodiments, the second solution issubstantially devoid of rare earth metal. This includes, by definition,being substantially devoid of rare earth metal and any salts or othercompounds including rare earth metal. Substantially devoid, as it isused with respect to the rare earth metal includes that amount or lessof rare earth metal that would not have an appreciable impact on thesupported catalyst, especially with regard to practice of thisinvention. In one or more embodiments, the second solution is devoid ofrare earth metal. In one or more embodiments, the concentration of anyrare earth metal, or rare earth metal salt, within the second solutionof certain embodiments is less than that amount that would provide thesupport, after drying, with an additional rare earth metal concentrationof 0.5, in other embodiments 0.3, in other embodiments 0.1, or in otherembodiments 0.05 wt % rare earth metal.

INDUSTRIAL APPLICABILITY

In one or more embodiments, the catalyst compositions of the presentinvention are used in oxychlorination processes to convert ethylene to1,2-dichloroethane. These processes are known as disclosed in, U.S. Pat.No. 5,292,703 and U.S. Publ. Nos. 2009/0054708, 2009/0298682,2010/0274061, 2006/0129008, and 2004/0192978, which are incorporatedherein by reference. In one or more embodiments, the process employs afluid bed reactor. In particular embodiments, the process employs abaffled bed reactor.

In one or more embodiments, the oxychlorination catalyst of thisinvention can advantageously be used in oxychlorination processes wherethe molar ratio of oxygen to hydrogen chloride (O₂/2HCl) approaches astoichiometric feed rate of 0.5. In one or more embodiments, the processoperates at a molar ratio of oxygen to hydrogen chloride (O₂/2HCl) ofless than 0.9, in other embodiments less than 0.7, in other embodimentsless than 0.64, in other embodiments less than 0.62, in otherembodiments less than 0.58, in other embodiments less 0.54, in otherembodiments less 0.52, in other embodiments less 0.5, in otherembodiments less 0.48, in other embodiments less than 0.46 and, in otherembodiments less 0.44 without becoming deleteriously sticky.

This process can be carried out as a once through process wherein anyunreacted ethylene is vented or otherwise removed, or in a recycleprocess wherein the unreacted ethylene is recycled back into thereactor. In the recycle process the ratio of HCl to ethylene will tendto be lower than 2 whereas in a once through process it will tend toapproach or be closer to 2 thus resulting in a overall HCl to ethylenemolar operating range of about 1 to about 2.

The catalyst compositions of the invention are highly efficientcatalysts for the oxychlorination of ethylene to EDC. The reactionprocess temperatures vary from about 170° C. to about 260° C., fromabout 180° C. to about 250° C., and more specifically from about 190° C.to about 240° C. Reaction pressures vary from atmospheric to as high asabout 200 psig. Contact times in the fluid bed and fixed bed catalysiscan vary from about 5 seconds to about 50 seconds (contact time isdefined here as the ratio of reactor volume taken up by the catalyst tothe volumetric flow rate of the feed gases at the reactor controltemperature and top pressure), and more preferably are from about 5seconds to about 35 seconds. The ratio of the ethylene, HCl, and oxygenreactants, based on the moles of HCl fed to the reactor, range fromabout 1.0 to about 2.0 moles of ethylene and about 0.5 to about 0.9 moleof oxygen per 2.0 moles of HCl. As previously mentioned, modernoxychlorination processes attempt to operate within the stoichiometricratio of about 1 to about 2 moles of HCl to 1 mole of ethylene.

TABLE I Total Composition Low mol per kg High mol per kg Low High Metalcatalyst catalyst Wt % Wt % Alkali (Wt % based on K) Embodiment 1 0.060.41 0.25 1.6 Embodiment 2 0.13 0.38 0.50 1.5 Embodiment 3 0.26 0.361.00 1.4 Embodiment 4 0.27 0.33 1.05 1.3 Alkaline Earth (Wt % based onMg) Embodiment 1 0.10 1.23 0.25 3.0 Embodiment 2 0.21 1.03 0.50 2.5Embodiment 3 0.31 0.93 0.75 2.25 Embodiment 4 0.41 0.82 1.0 2.0 RareEarth (Wt % based on La) Embodiment 1 0.00 0.18 0.00 2.5 Embodiment 20.04 0.17 0.50 2.3 Embodiment 3 0.05 0.16 0.75 2.2 Embodiment 4 0.070.14 1.0 2.0

TABLE II First Solution Low mol per kg High mol per kg Low High Metalcatalyst catalyst Wt % Wt % Alkali (Wt % based on K) Embodiment 1 0.060.41 0.25 1.6 Embodiment 2 0.13 0.38 0.5 1.5 Embodiment 3 0.26 0.36 1.01.4 Embodiment 4 0.27 0.33 1.05 1.3 Alkaline Earth (Wt % based on Mg)Embodiment 1 0.21 1.03 0.5 2.5 Embodiment 2 0.29 0.82 0.7 2.0 Embodiment3 0.35 0.70 0.85 1.7 Embodiment 4 0.41 0.62 1.0 1.5 Rare Earth (Wt %based on La) Embodiment 1 0 0.18 0 2.5 Embodiment 2 0.04 0.17 0.5 2.3Embodiment 3 0.05 0.16 0.75 2.2 Embodiment 4 0.07 0.14 1.0 2.0

TABLE III Second Solution Low mol per kg High mol per kg Low High Metalcatalyst catalyst Wt % Wt % Alkaline Earth (Wt % based on Mg) Embodiment1 0 0.62 0.06 1.5 Embodiment 2 0.05 0.125 Embodiment 3 0.07 0.53 0.181.3 Embodiment 4 0.10 0.41 0.25 1.0 Rare Earth (Wt % based on La)Embodiment 1 0 0.18 0 2.5 Embodiment 2 0.04 0.17 0.5 2.3 Embodiment 30.05 0.16 0.75 2.2 Embodiment 4 0.07 0.14 1.0 2.0

In order to demonstrate the practice of the present invention, thefollowing examples have been prepared and tested. The examples shouldnot, however, be viewed as limiting the scope of the invention. Theclaims will serve to define the invention.

EXAMPLES

The catalysts were prepared by impregnating an alumina support with anaqueous solution of the desired metal chlorides using a two-stepimpregnation process, with the exception of Comparative Example 1, whichwas prepared using a single-step impregnation. The metal chloridesolution was added to the alumina support as it was rotated and stirredin a ceramic dish. Each impregnation was carried out at roomtemperature. Subsequent to each impregnation, the ceramic dishcontaining the catalyst was placed over a steam bath for the initialdrying phase (about 4 to 6 hours) and then heated up to 180° C. for thefinal drying phase (up to 16 hours).

The alumina support was purchased under the tradename Catalox SCCa25/200 (Sasol) and was characterized by a pore volume of 0.45 mL/g, asurface area of 200 m²/g, a particle size distribution where 2.0% of theparticles were smaller than 22 μm, 9.0% of the particles were smallerthan 31 μm, 29% of the particles were smaller than 44 μm, 85% of theparticles were smaller than 88 μm, and 98% of the particles were smallerthan 125 μm). The volume of each solution employed corresponded to90-115% of the pore volume of the support.

The aqueous solutions were prepared by employing one or more of thefollowing metal salts: CuCl₂.2H₂O, KCl, MgCl₂.6H₂O, LaCl₃.7H₂O,CeCl₃.7H₂O, PrCl₃.6H₂O. Table IV provides the details for the metaldeposited on the support for each sample catalyst, and the skilledperson can, without undue calculation or experimentation, determine theamount of metal salt to be added to a given solution in order to achievethe desired metal loading. For example, Comparative Example 2, which wasprepared by a two-step impregnation, included the preparation of a firstsolution by combining 9.73 g of CuCl₂, 2.48 g of KCl, and 5.72 g ofMgCl₂, and dissolving the same in water to achieve 35.08 ml of water(which amount includes 9.1 g water of hydration associated with thesalts). This solution was combined with 82.07 g of alumina. Upon drying,the finished catalyst, after the first impregnation step, included themetal provided in Table IV, with the understanding that all of themetals adhered to the support. Following the first impregnation, asecond solution was prepared by combining 9.94 g of of CuCl₂, and 1.37 gof MgCl₂, and dissolving the same in water to achieve 37.9 ml of water(which included 4.22 g water of hydration associated with the salts).This solution was combined with 88.68 g of catalyst composition from thefirst step, and then dried to provide a 100 g sample of catalystcomposition having the metal adhered thereto as reported in Table IV;i.e. 100 g of the finished catalyst composition included 8.78 g Cu, 1.15g K, and 1.64 g Mg, based on the weight of metal associated with thecorresponding absorbed or adhered salts.

Table IV also provides the amount of metal included in the solutionemployed for the second impregnation, as well as the molar ratio of theMg to Cu added in the second impregnation step. With reference to againto Comparative Example 2, the skilled person will appreciate that 9.94 gof of CuCl₂ corresponds to 4.7 g Cu, and 1.37 g of MgCl₂ corresponds to0.35 g Mg. These amounts provide a molar ratio of Mg to Cu ratio of 0.19(i.e. 0.0144/0.0740).

Still further, Table IV provides the amount of added metal imparted bythe second impregnation step. Consistent with the explanation providedabove, this amount is calculated based upon the differential between theweight percent of metal present on the support after the firstimpregnation step and the weight percent of metal present on the supportafter the second impregnation step and represented as a weight percentadded amount based upon the total weight of the finished catalystcomposition. For example, and with reference again to ComparativeExample 2, the amount of Cu present within the catalyst compositionafter the first impregnation step was 4.6 wt %, and the amount of Cupresent within the catalyst composition after the second impregnationstep was 8.78 wt %, and therefore the differential was 4.18 wt % basedupon the total weight of the total finished catalyst composition.

A laboratory-scale reactor was employed to analyse the usefulness ofeach catalyst composition. The laboratory-scale reactor included atubular glass reactor with an internal cross-sectional area of 2.78 cm².The reactor was operated at atmospheric pressure and was filled with anamount of catalyst leading to a fluidised bed height of 20±1.0 cm. Thefeed gas included 6.96 mmole/minute N₂, 4.87 mmole/minute of ethylene,5.32 mmole/minute of HCl, and a variable O₂ to 2HCl molar feed ratioranging from 0.6 down to 0.46. The reaction temperature was measuredwith a centered thermocouple in the fluidized bed and regulated onbehalf of external electric heating. The reaction temperature rangevaried as shown in Tale IV (e.g. 200 and 235° C.). HCl in the feed andin the product gas was measured via titration. N₂, C₂H₂, O₂, CO_(x), andchlorinated hydrocarbons were measured via GC (HP 6890 Series; Columntypes—1) Vocol glass capillary column (60 meter; 0.75 mm ID; 1.5 micronfilm thickness. 2) 80/100 Porapak N column (12 foot×⅛ inch, stainlesssteel). 3) 60/80 molecular sieve, 5 angstrom (6 foot×⅛ inch);Detectors—2 TCD's. Detector B (Vocol column) Detector A (molsieve/Porapak); One TCD is used to detect light gases, such as O₂, N₂,and CO from the molecular sieve column, and heavier gases, such as CO₂and ethylene as well as lighter chlorinated hydrocarbons such as vinylchloride and ethyl chloride from the Porapak column. A second TCD wasused to detect the remaining heavier chlorinated hydrocarbons from theVocol column starting with chloroform, including EDC and other heavierchlorinated by-products.).

Based on the analytics and the feed gas amounts, the HCl conversion, theethylene conversion, the EDC selectivity and the selectivity of thedifferent oxidised and chlorinated by-products was calculated. Thesticking resistance was evaluated by gradually lowering the oxygen to2HCl ratio at a given operating temperature to the point where visualagglomerations of the catalyst, fluctuations in the differentialpressure or sudden changes in selectivity occurred. More specifically,the observation of catalyst stickiness was achieved both visually and bymeasuring the change in the pressure drop across the fluidized bed usinga differential pressure metering device. Under typical fluidization ornon-sticky conditions the catalyst was moving freely and smoothly in thereactor with a fairly constant effluent gas exit rate where gaseouspockets or bubbles observed within the bed are of small diameter andminimal in quantity. This visual observation corresponded to a measureddifferential pressure that contained very little noise or fluctuation inthe differential pressure value that was observed during goodfluidization or non-sticky conditions.

As the catalyst became sticky, the fluid-bed height increased by up to10% of the normal bed height prior to fluidization failure or the onsetof severe catalyst stickiness. At the failure point, slugging of thecatalyst bed was observed where large gas pockets are formed and thecatalyst was no longer fluidizing well but instead was showing particleclustering or agglomeration. Additionally, the pressure differentialobserved across the fluid-bed became unstable resulting in larger thannormal swings relative to when operating under non-sticky conditions. Atypical differential pressure reading may have varied by +/−1 mbar undernon-sticky operating conditions. This “low noise” pressure readingrelates to good fluidization or non-sticky operating conditions. Whenthe differential pressure reading consistently varied by more than +/−3mbar, this “high noise” condition represented the point of poorfluidization or catalyst stickiness.

TABLE IV Sample No. Comparative Inventive 1 2 3 1 2 3 4 5 TargetedComposition (Step 1) Cu (wt %) 8.7 4.6 4.3 4.2 4.2 4.6 4.4 4.6 K (wt %)0.03 1.3 1.1 1.11 1.11 1.2 1.2 1.3 Mg (wt %) 1.15 1.46 1.3 1.31 1.30 1.51.2 1.46 La (wt %) 0.34 — 1.2 1.2 1.2 0.75 0.9 — Ce (wt %) 0.16 — 0.40.4 0.4 0.25 0.3 — Pr (wt %) — — 0.4 0.4 0.4 0.25 0.3 — TargetedComposition (Step 2) Cu (wt %) — 4.7 1.81 4.2 4.2 4.6 4.7 4.7 Mg (wt %)— 0.35 — 0.4 0.4 0.45 0.5 0.5 Mg:Cu (Molar Ratio) N/A 0.19 N/A 0.25 0.250.26 0.28 0.28 Total Composition (Finished) Cu (wt %) 8.7 8.78 5.95 7.967.96 8.67 8.58 8.75 K (wt %) 0.03 1.15 1.06 0.99 0.99 1.06 1.06 1.15 Mg(wt %) 1.15 1.64 1.25 1.57 1.56 1.78 1.56 1.79 La (wt %) 0.34 — 1.151.07 1.07 0.66 0.79 — Ce (wt %) 0.16 — 0.38 0.36 0.36 0.22 0.26 — Pr (wt%) — — 0.38 0.36 0.36 0.22 0.26 — Added Metal Cu (wt %) N/A 4.18 1.653.76 3.76 4.07 4.18 4.15 Mg (wt %) N/A 0.18 N/A 0.26 0.26 0.28 0.36 0.33Experimental Results Temperature(s) 230 220 235 220 230 215 230 230 225220 230 At O2/2HCl ratio >0.57 >0.57 >0.57 <0.50 <0.50 <0.50 <0.50 <0.50Sticky (Y/N) Y Y Y N N N N N Meets or exceeds N Y Y Y Y Y Y Y 99.5% HClConversion and 98.0% EDC Selectivity (Y/N) Meets or exceeds N N Y Y Y YY Y 99.5% HCl Conversion and 99.0% EDC Selectivity (Y/N)

Various modifications and alterations that do not depart from the scopeand spirit of this invention will become apparent to those skilled inthe art. This invention is not to be duly limited to the illustrativeembodiments set forth herein.

What is claimed is: 1-10. (canceled)
 11. A process for producing acatalyst for the oxychlorination of ethylene to 1,2-dichloroethane, theprocess comprising the steps of: (i) impregnating, within a first step,an alumina support with a first aqueous solution including copper, analkaline earth metal, and an alkali metal to thereby form a firstcatalyst component; and (ii) impregnating, within a subsequent step, thefirst catalyst component with a second aqueous solution including copperand alkaline earth metal, where the second aqueous solution issubstantially devoid of alkali metal, to thereby form the supportedcatalyst.
 12. The process of claim 11, where the alkaline earth metal ismagnesium, and where said second aqueous solution includes a magnesiumto copper molar ratio of greater than 0.19. 13-14. (canceled)